May 28 (UPI) -- Elon Musk, who personally spent $277 million to bring Donald Trump back to the White House, said Wednesday night he is leaving the Trump administration after working to slash the size of the federal government through the Department of Government Efficiency.

Musk, the world's richest man with a net worth of $421.2 billion, according to Forbes, can work for 130 days in a calendar year as a special employee. His full-time tenure would end on Friday after joining Trump in the White House for the Jan. 20 inauguration.

Musk posted to X, the social media platform he owns: "As my scheduled time as a Special Government Employee comes to an end, I would like to thank President @realDonaldTrump for the opportunity to reduce wasteful spending. The @DOGE mission will only strengthen over time as it becomes a way of life throughout the government."

Musk told reporters earlier this week that he plans to focus more on his businesses: Tesla, SpaceX and artificial intelligence startup xAI, which now includes X.

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